Previous research on non-scientific medical systems has focused either on modern unorthodox practices (e.g., chiropractic, naturopathy) or traditional healing (e.g., curanderismo, herbal medicine). Research on strategies for handling illness rarely considers non-scientific help as a possibility. Studies which examine the choice between the two systems are few in number and limited in scope. This study proposes a general model in which the factors which predispose the continued use of traditional medicine, in addition to or instead of scientific medicine, can also be used to explain the currently increasing use of modern unorthodox practitioners. Recent surveys, particularly efforts by the World Health Organization, permit a comparative, secondary analysis on the use of scientific medicine. The proposed analysis is three fold. First, using data from approximately 12 countries, and internal analysis (via techniques of regression analysis) will focus on issues of quality of care, barriers to entry into scientific medicine (particularly for the disadvantaged), and the nature of the disease. Second, a macro-level analysis (using regions as units) will explore how the characteristics of a society (e.g., developmental, medical and governmental) affect the propensity to use non-scientific medicine. Finally, for the United States, as over-time analysis of this decision-making process will be considered. This will be done by (a) correlating trends in the use of non-scientific medicine with other independent societal trends (e.g., changes in government financing of scientific medicine), and (b) exploring the cohort, age and period effects (via techniques of tabular display and analysis of covariance). In this way, a contribution can be made to understanding how variation in individual, societal and temporal factors affects the use of other systems of medical care.